A power provide is applied to reduce mains or 3 period electrical energy, generally at 240 Vac or 440 Vac all the way down to a voltage that's usable, including twelve Vdc. The PSU also converts The existing ranking, in the form of AMPS, to some amount which is safe https://powersuppliesrepair45443.blogadvize.com/36941254/getting-my-power-supplies-repair-to-work